1. Field of the Invention
The present invention relates to a lens barrel that holds a zoom lens including three lens groups and can be extended and collapsed and an imaging apparatus including the lens barrel.
2. Description of the Related Art
In recent years, the size and thickness of imaging apparatuses have been reduced. In addition, there is a demand for an imaging apparatus with a small size and a small thickness that includes a lens barrel which holds a zoom lens including a plurality of lens groups and can be extended and collapsed.
For example, a lens barrel has been proposed which includes a rotating cylinder (cam cylinder) having cam grooves provided in the inner and outer surfaces thereof (for example, see Japanese Patent No. 3842087).
In the lens barrel disclosed in Japanese Patent No. 3842087, the cam grooves are provided in the outer surface and the inner surface of the rotating cylinder (cam cylinder). Therefore, according to the lens barrel, it is possible to move a plurality of lens groups in the optical axis direction without any failure and reduce the size of the lens barrel in the optical axis direction.
However, the cam grooves provided in the outer surface and the inner surface of the rotating cylinder (cam cylinder) overlap each other in a perspective view of the lens barrel as viewed from a direction perpendicular to the optical axis. In this case, the strength of the overlap portion is less than that of other portions.